To set the price for your chests, head over to My Collections and select Manage on any of the collections you'd like to configure. Then, on the upper-right side of the page, click on Packs and Prices, as shown in the screenshot below:
There you can set any price you want on your chests. The minimum amount for 1 single chest is €1.99 (or $1.99). It's important to keep in mind that payment platforms take a fee from the total payment amount.
Paysafecard takes 15%, PayPal and credit card payments take $0.05 and 5%. Payment platform fees are external to Streamloots, so they could vary.